This invention relates to an intermediate housing for a fuel-operated heater that, in particular, is intended as an auxiliary heater for vehicles.
From German Pat. No. 24 32 850, a fuel-operated heater for vehicles is known that has an intermediate housing of the initially mentioned type. A driving motor, a combustion air blower driven by it, starting and control devices and a burner unit are housed in this intermediate housing. In this case, the driving motor at both of its axially opposite ends is disposed in the intermediate housing. In addition, a heat exchanger can be mounted to the intermediate housing as an axial extension of said housing via a fastening flange, said heat exchanger concentrically surrounding a combustion chamber. An exhaust gas outlet connection piece is a portion of the part of the heater forming the heat exchanger.
This invention has the objective of providing an intermediate housing for a heater of the initially mentioned type that combines several functions in itself and that serves as a central connecting unit for the combustion air blower, the fuel supply and for the exhaust gas discharge as well as for the ignition device and other electrically powered components. In addition, the intermediate housing according to the invention has the purpose of making possible a fast and simple mounting of the heater via a mounting arrangement that is connected firmly with a vehicle. In this case, especially an extremely compact and space-saving construction of the heater as a whole is to be achieved.
According to the invention, the intermediate housing is developed in such a way that a unit consisting of the driving motor and a combustion air blower, that is preferably a side-channel blower, is mounted to the intermediate housing directly at a combustion air blower end thereof via an interposed elastic element. For this purpose, a circumferential support is developed in the intermediate housing that has a conical shape and serves as a stop during the axial insertion of the unit consisting of the driving motor and the combustion air blower. The axially opposite end of the driving motor, or of this unit, is also elastically mounted, such as by a motor cap fastened at the intermediate housing that interacts with an elastic element that is preferably arranged at the corresponding end of the driving motor. Preferably, the elastic elements are rings and permit, at the same time, a sealing of the bearing points. In the case of the intermediate housing, the bearing surface for the unit consisting of the driving motor and the combustion air blower is formed directly by it.
In addition, the elastic bearing of this unit prevents a direct structure-borne noise transmission to the intermediate housing, and the intermediate housing permits, in conjunction with the motor cap, an encased housing of the driving motor and of the combustion air blower resulting in an operation of such a heater that makes very little noise.
According to the another aspect of the invention, the intermediate housing is designed in such a way that, on one side of the intermediate housing, the combustion air intake connection piece, the fuel feed line receiving opening and the exhaust gas outlet connection piece are formed axially one behind the other as close as possible. Since in the intermediate housing the connections for the combustion air supply system, the fuel supply system and for the exhaust gas discharge are integrated and are arranged as close to one another as possible, not only the mounting of such a heater in connection with a mounting arrangement is facilitated, but especially also the development of the heat exchanger is simplified because, in this case, the connections, such as for the exhaust gas discharge, do not have to be taken into account.
Preferably in the area of the outer surface of the intermediate housing, around the supply and discharge connections, support feet are also formed that, at the same time, interact with a mounting arrangement that can be attached to the vehicle. These support feet form supporting points for the heater and are distributed over a surface that is as large as possible in order to provide support, at the mounting arrangement, that is secure with respect to tilting. A safety device for the heater may also be provided that is preferably developed as a contact-actuated auxiliary switch and interacts with the mounting arrangement in such a way that, when the heater is detached from the mounting arrangement, the heater is forcibly switched off by the safety device for the heater. This also takes into account the safety requirements with respect to heaters of this type that are becoming stricter in general.
According to a preferred embodiment of the invention, at the side of the intermediate housing opposite that having the combustion air, fuel and exhaust gas connections, a trough-shaped receiving space is formed in which all electrical connections and also the ignition device, as well as a flame monitoring device, can be housed. This receiving space is easily accessible so that the devices of the heater that have to be electrically energized are also easily accessible when necessary. In addition, my means of such a central arrangement of the electric connections of the heater in the intermediate housing, it is made possible that the electric components can be examined separately without any taking-apart of the heater. As a result, the operational reliability of such a heater can be improved. Preferably, this receiving space is connected with the intake space of the combustion air fan via an opening and is closed off tightly in the direction of the outside by means of a cap, that can be screwed together with the intermediate housing and that contains the counterparts of the electrical connections so that cap also, at the same time, forms a connector unit for the electrical connections and closes the receiving space in a gastight way in order to prevent an escape of combustion gases. In addition, via this space, an adjusting device for the combustion air volume is also accessible so that an adjustment of the combustion air volume provided by the combustion air blower can take place without difficulties, even though the heater is mounted in place by the mounting arrangement.
According to another advantageous development of the invention, devices are also integrated into the intermediate housing of the heater that permit the fastening of the heater to the mounting device. For this purpose, at least one passage is provided in the receiving space and another passage is provided in the intermediate housing at a corresponding aligned point, through which at least one fastening screw can be guided that connects the heater with the mounting arrangement. Preferably, for the fastening of the heater at the mounting arrangement, two fastening screws are provided that can be fitted through correspondingly developed passages in the intermediate housing. By means of this development according to the invention, the intermediate housing makes it possible that the whole heater can be fastened rapidly into the condition of usage and, if necessary, be detached again. The reason is that for the mounting and dismounting only the cap of the receiving space must be removed without the requirement that, for this purpose, outer casing parts of the heater have to be removed, and the fastening screws can then be rightened or loosened.
Advantageously, the intermediate housing also achieves the objective of serving as an attachment part for cup-shaped casing parts or casing halves that are preferably formed of sheet metal and which, by means of sheet-metal screws, can be fastened to the intermediate housing.
According to another advantageous development of the invention, the intermediate housing, at its exterior surface, carries axially extending cooling ribs, the axial course of which is preferably interrupted by the fact that the cooling ribs are arranged staggered with respect to one another in a circumferential direction. The cooling ribs that are located in proximity of the fastening flange for the heat exchanger are, therefore, set off from those cooling ribs that are arranged at the remaining part of the intermediate housing so that the residual heat from the heat exchanger is not distributed along the whole length of the housing and the heat transfer of the heat exchanger can be designed to be more efficient.
As demonstrated, the intermediate housing according to the invention permits the putting-together of several different functions in one combination in such a way that it serves as a central connection unit for the electrical parts as well as a bearing for the driving motor and also for the attachment of the heater to a mounting arrangement. As a result, surprising simplifications are obtained with respect to the construction and the mounting of a heater having such an intermediate housing.
These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, a single embodiment in accordance with the present invention.